1. Field of the Invention
The present invention relates to compound bows used in archery, including dual and single cam compound bows. More particularly the present invention relates to a buss cable positioner for laterally locating the buss cables out of the way of the area of space used for the arrow and for sighting. Still more particularly, the present invention relates to a buss cable positioner which eliminates limb torquing.
2. Description of the Related Art
Simple archery bows are composed of a bow member (or back) characterized by a handle having connected thereto on each side thereof a flexibly resilient limb, and a bow string connected with opposite ends of the bow member. The archer places the nock of an arrow against the nocking point of the bow string and then draws the bow string, thereby causing the bow member to resiliently flex at the limbs. This flexing of the bow member supplies tension to the bow string and stores potential energy (draw energy). When the bow string is released, the tension of the bow string applies a force to the arrow, whereupon the potential energy of the bow member is captured by the arrow in the form of kinetic energy. While such an archery bow has the advantage of being simply constructed, it suffers from the need of the archer to continuously supply draw pull to keep the bow member resiliently flexed. Another serious disadvantage is the essentially instantaneous application of bow string force upon the arrow at the moment the bow string is released, with consequent degredation of accuracy due to the imparted shock. An improved example of a simple archery bow using springs to reduce bow string shock is described in U.S. Pat. No. 4,570,606 to Peck.
These problems have been addressed in the past with varying degrees of success, wherein it is an object to provide an archery bow having a draw pull let-off feature, while yet providing a high level of draw energy for imparting ample speed to the arrow when released. In this regard, compound archery bows have been devised toward addressing this object, generally utilizing a rigging of the bow string with respect to one or more cams or pulleys which are rotatively mounted with respect to the bow member via buss cables. As the bow string is pulled back, the limbs of the bow member are caused to resiliently flex, while rotation of the cams or pulleys as the bow string is pulled back causes the force on the bow string to be high during pull back of the bow string and then let-off as the maximum draw point is achieved. Examples of such compound bows are described in U.S. Pat. No. 4,718,397 to Remick, U.S. Pat. No. 4,461,267 to Simonds et al, U.S. Pat. No. 4,562,824 to Jennings, and U.S. Pat. No. 4,519,374 to Miller. Imaginative and interesting variations on this principle are found in U.S. Pat. No. 5,045,463 to Colley et al, U.S. Pat. No. 4,817,580 to Butterfield, U.S. Pat. No. 3,851,638 to Alexander, and U.S. Pat. No. 2,714,377 to Mulkey.
As the bow string is drawn, the limbs of the bow resiliently bend in a bow plane which bisects the bow member. The arrow, bow sights, and bow string are all located in, or closely centered in, this plane; and, problematically, so, too, are the buss cables. While the nock of the arrow engages the nocking point of the bow string so that there is no conflict in position therebetween, this is not the case for the buss cables. Since the buss cables fall in the bow plane between the bow string and the bow member, they conflict positionally with the arrow and the bow sights. Accordingly, it is necessary to move the buss cables laterally with respect to the bow plane so that they are out of the way of the arrow and the bow sights.
FIGS. 1 and 1B depict a conventional compound bow 10. The bow string 12 is strung between the limbs 16a, 16b of the bow member 14. The bow string 12 lies substantially on the bow plane P (see FIG. 1B), wherein the bow plane is aligned with the bow string and bisection of the bow member 14. Buss cables 18a, 18b are positioned between the bow member 14 and the bow string 12 in a narrow zone centered on the bow plane P. The buss cables 18a, 18b are laterally repositioned a distance D (see FIG. 1B) with respect to the bow plane P via a slide-type positioner 20 in order to get the buss cables out of the way of the arrow and the sights of the compound bow at the arrow nocking point a lateral distance Dxe2x80x2. The rod 22 of the slide-type buss cable positioner 20 is connected with the bow member 14 and is located at a position laterally displaced with respect to the bow plane P (wherein in FIG. 1B the bow plane is at the bow string). The slide 24 of the slide-type positioner 20 has a concave rod seat which slidingly interfaces with the rod 22. Opposite the rod seat, the slide 24 has two concave cable guides for receiving, respectively, each of the buss cables 18a, 18b at the desired distance D from the bow plane.
In operation, as the bow string is drawn back, the buss cables interact with the cam 26 (or cams in two cam compound bows) to cause the limbs to be resiliently bent toward each other in the bow plane. The buss cables are prevented from encroaching too near the bow plane by action of the slide-type positioner 20, so that an arrow and the sights of the compound bow are not interfered therewith.
Problematically, however, the buss cables have been forced laterally with respect to the bow plane by the slide-type positioner 20. This lateral displacement results in a force F perpendicular to the bow plane P (see FIG. 1B). This perpendicular force F is transmitted in one direction to the handle of the bow member 14 and in the opposite direction to the limbs 16a, 16b, resulting in a limb torque off the bow plane P. This limb torque results in inaccuracy in arrow aiming, since the bow string is not precisely being tensioned in the bow plane by the limbs. Further, the slide-type positioner 20 suffers from associated vibration, noise and frictionally introduced hesitation effects as the slide moves along the rod (see arrow S) in concert with buss cable travel associated with the peripheral contact of the buss cables with the cam(s).
Accordingly, what yet remained needed in the art was a positioner for buss cables which effects lateral repositioning of the buss cables, but, optimally, did not introduce any limb torque.
A major breakthrough in compound bow technology was forwarded by Paul H. Bunk in his U.S. Pat. 5,722,385, the entire disclosure of which is hereby herein incorporated by reference. Bunk addressed the issue of buss cable positioner limb torque by providing a guide member which serves to move the buss cables out of the way or the arrow, yet ensures the limbs see no torque.
According to Bunk, and as shown at FIG. 2, a torqueless buss cable positioner 100 is characterized by a guide member 122 pivotally mounted to a compound bow 102. The compound bow has a bow member 106, a handle section 108 and limbs 110a, 110b. Cams 112a, 112b are rotatably connected, respectively, to the end of each of the limbs. The compound bow further includes a bow string 104 which is drawn back into the bow plane of the compound bow and a pair of buss cables 116a, 116b. The guide member 122 includes a frame 126, a first pulley set 128 connected to one end of the frame, a second pulley set 130 connected to the other end of the frame, and a third pulley set 132 connected preferably medially to the frame. The frame is shaped, such as for example by a curve, whereby the first and second pulley sets mutually define an alignment axis, but the third pulley set is laterally displaced relative to the alignment axis. The frame is optimally structured and mountably positioned relative to the bow member so that the grooved periphery of each of the first and second pulley sets is located generally at the bow plane and the grooved periphery of the third pulley set is laterally displaced off from the bow plane a distance determined by the required buss cable displacement for the particular compound bow to which the torqueless tension cable positioner is utilized. As the bow string is drawn back in the bow plane, the entry location of the buss cables at the groove periphery of the cams of the compound bow change in distance from the axis of rotation of the cams at the limbs due to cam rotation and limb bending. To accommodate this movement of the buss cables, the guide member 122 pivots via the frame 126 being pivotally mounted to the bow member so that the pulley sets can follow the resulting travel of the buss cables. The pivotability of the guide member relative to the bow member is provided by pivotal connection of the frame to a mounting bracket 124 which is, in turn, mounted to the bow member, preferably with a spring biasing. It is also preferred for the mounting bracket, itself, to be pivotally mounted to the bow member, also, preferably, with its own spring biasing.
While the merits of the Bunk concept are legion, there yet remains a need to simplify the mechanics, particularly a need to eliminate parts and pivoting of the parts.
The present invention is a torqueless buss cable positioner for a compound bow which is fixedly mounted thereto, whereby the buss cables are displaced from the bow plane, yet, optimally, the buss cables do not subject the limbs to any force component perpendicular to the bow plane.
The torqueless buss cable positioner according to the present invention provides a guided path for the buss cables which includes first and second outboard guidance components for guiding the buss cables generally in the bow plane and an inboard guidance component for guiding the buss cables laterally off from the bow plane. The first and second outboard guidance components optimally ensure that the limbs are not subjected by the buss cables to any component of force perpendicular to the bow plane, and the inboard guidance component ensures that the buss cables are laterally displaced in relation to the bow plane sufficiently to be out of the way of the arrow and the sights of the compound bow. Further, the torqueless buss cable positioner according to the present invention has an inherent flexibility which obviates pivoting in order to compliantly align with movement of the cams/wheels as the bow string is drawn/released.
The torqueless buss cable positioner according to the present invention is characterized by a guide member fixedly mounted to the bow member, wherein by the term xe2x80x9cfixedly mountedxe2x80x9d is meant that the guide member is non-pivotally mounted relative to the bow member. The guide member includes a flexible (preferably resiliently flexible) guide bar, a first outboard guidance component connected to one end of the guide bar, a second outboard guidance component connected to the other end of the guide bar, and an inboard guidance component connected preferably medially to the guide bar. The guide bar is shaped, such as for example by a curve, whereby the first and second outboard guidance components mutually define an alignment axis, but the inboard guidance component is laterally displaced relative to the alignment axis (that is, displaced perpendicular to the bow plane).
In the preferred embodiment, the first outboard guidance component is composed of a first pulley set rotatably connected to one end of the guide bar, the second outboard guidance component is a second set of pulleys rotatably connected to the other end of the guide bar, and the inboard guidance component is a third pulley set rotatably connected to a medial portion of the guide bar. The guide bar is fixedly connected to the bow member by a rigid connection member, preferably in the form of a rigid mounting rod fixedly connected to both the guide bar and the bow member.
The guide bar is optimally structured and mountably positioned relative to the bow member so that the grooved periphery of each of the first and second pulley sets is located generally at the bow plane and the grooved periphery of the third pulley set is laterally displaced off from the bow plane a distance determined by the required buss cable displacement for the particular compound bow to which the torqueless tension cable positioner is utilized. As the bow string is drawn back into the bow plane, the entry location of the buss cables at the groove periphery of the cam/wheel of the compound bow change in distance from the axis of rotation of the cam(s) at the limb(s) due to cam rotation and limb bending. To accommodate this buss cables movement, the guide bar is flexible in the bow plane, but is generally rigid along the other two planes perpendicular thereto. Accordingly, the guide bar flexes so that the first and second pulley sets can follow the resulting travel of the buss cables as the bow string is drawn or released.
Accordingly, it is an object of the present invention to provide a torqueless buss cable positioner for compound bows, whereby the buss cables are laterally displaced with respect to the bow plane, yet, optimally, the limbs of the bow are not subjected to a perpendicular component of force by the buss cables.
It is an additional object of the present invention to provide a torqueless buss cable positioner for compound bows, wherein a guide member is fixedly mounted to the bow member, but includes a flexible guide bar which flexes (or bends) in compliant alignment with movement of the buss cables as the bow string is drawn or released.
These, and additional objects, advantages, features and benefits of the present invention will become apparent from the following specification.